Mercury vapor or arc type rectifier



Oct. 19, 1937. LATOUR 2,096,523

MERCURY VAPOR OR ARC TYPE RECTIFIER Filed May 15, 1933 v 2 sheets-sheet 'l Oct. 1 9, 1937. T 2,096,523

MERCURY VAPOR OR ARC TYPE RECTIFIER Filed May 15, 1953 2 Sheets-Sheet 2 Patented Oct. 19, 1937 UNITED STATES 2,096,523 MERCURY VAPOR 0R ARC TYPE RECTIFIER Marius Latour, San Sebastian, Spain Application May 15, 1933, Serial No. 671,246

In France May 25, 1932 5 Claims.

This invention relates to rectifying apparatus for alternating currents of any frequency, the rectifiers being of the mercury vapor or are type having electrodes controlled by internal grids or external sheaths or coatings. With a view to regulating the strength of the current supplied or passed by the rectifier, various proposals have already been made to determine'the moment of ignition of the anode discharge or arc in relation to the positive half-period of the anode voltage, by applying to the control grids or sheaths an alternating voltage essentially of the same frequency as the anode voltage but of which the phase can be varied in relation thereto.

According to the present invention, the desired result is obtained not with a control (grid) voltage of the same frequency as the anode voltage, but with one which is a harmonic of the anode voltage or with one obtained by the superposition of voltages which are harmonics of the frequency of the anode voltage, the harmonic-frequency voltage thus applied to the control electrode or grid being variable in magnitudeand in phase in order to obtain the desired regulation of the output current. The phase-variation between the grid voltage'and the anode voltage regulates the strength of the current traversing the rectifier by preventing the formation of the are for more than a desired fraction of the half-period during which the anode is positive in relation to the cathode, as in the known arrangements referred to above, but whereas in the known proposals the grid voltage was of the same frequency as the. anode voltage, I obtain a-more convenient regulation of the outputcurrent by employing a grid voltage having a frequency which is a harmonic of the frequency of the anode voltage. Further, by employing a grid voltage representing the superposition of voltages each having a harmonic frequency relation to the anode voltage, I obtain a wave-form which provides even better results than the sinusoidal voltage of harmonic frequency.

The invention is hereafter more particularly described with reference to the accompanying drawings, in which:

Fig. 1 represents by way of example, the relation of the anode voltage and control voltage in one form of carrying out the invention.

Fig. 2 represents the rectified voltage obtained.

Fig. 3 is a diagram of one arrangement for carrying out the invention, and

Fig. 4 represents a voltage obtained in this arrangement.

Fig. 5 represents diagrammatically the practi cal application of the arrangement shown in Fig. 3.

Fig. 1 illustrates an alternating anode voltage I and a control (grid) voltage II, the latter being a composition of harmonics corresponding to a frequency twice that of the anode voltage I. It can be seen at once that the progressive advance of curve II towards the right relatively to the voltage curve I, causes the ignition of the are at varying points on the positive half-wave of the anode voltage. The component harmonics forming the control voltage 11 might be regulated separately orjointly in magnitude and in phase, to give any desired form to the curve II. There might be superposed on these harmonics a voltage of the same frequency as the anode voltage, so as to provide for modifying the magnitude or the sign (positive or negative) of the control voltage, or there might even be superposed a direct current voltage upon the harmonics.

, It may be'remarked, moreover, that an alternating current rectifiedby an apparatus of cathode type is itself a generator of harmonic voltages. If there be considered the rectified current furnished by a two-anode rectifier, see Fig.

2, it will be seen that it contains; essentially the second harmonic of the original-frequency: v.If,

the rectified current of which'the wave-form is given by Figure 2, be passed through a resistance R1 (Figure 3), and if there be opposed to the ohmic fall of potential thus caused in this re-- sistance R1 a continuous voltage E1 acting through a resistance'Rz of high value, therewill be obtained 'across the terminals of the resistance R2 an alternating voltage of wave-form resem bling that represented by Fig. 4; from thisa. suitable harmonic voltage for replacing that indicated by the curve II in Fig. 1, can be produced readily and in good condition as regards economy and efficiency, by making use of the phenomena of saturation in magnetic circuits.

A voltage curve of similar wave-form would its primary winding. The rectified current will and a frequency double that of the supply current.

In rectifiers with two or more anodes, the same harmonic voltage can feed in parallel the control sheaths or grids corresponding to two anodes in phase opposition, in such a manner that there is thereby obtained a considerable reduction or simplification of the apparatus and auxiliary regulating circuits. This arrangement might even be extended to provide a single control sheath or grid common to two anodes. I

In Fig. 5, the rectifier R provided with six anodes a a and six grids g g is fed by the six-phase transformer T. The phase shifter or regulator T1 is provided with three secondary windings S, S and S" which feed the tubes 1, r and r", each having two anodes; only one of these tubes need be considered, the other two being connected in similar ways. The tube 1 passes rectified (pulsating) current through the adjustable resistance R1, the direct current source E1 opposing the voltage which appears at the ends of the resistance R1. A voltage of double frequency is given off across the resistance R2; one end of this resistance is connected to the cathode of the tube 1', the other end being led through grid-current limiting resistances R'g and R"g to two grids g and g corresponding to anodes in opposite phase relation to one another. The transformer T2 produces secondary voltages of the same frequency as the anode voltage, all the transformers T, T1, T2 having their primary windings connected to the same source. The

secondary windings of the transformer T2 are connected to the grid resistances Rg, R'g, Rg, whereby the grids g g g are raised to alternating potentials of the same frequency as the anode voltage, said alternating potentials being superposed upon the: double-frequency voltages derived from the resistances R2, R2, R"2. The connections of the transformer T2 to the current limiting resistances Rg, Rg, R"g are made in such a way that the grid voltage is in oppositionto the anode voltage.

grids formed by a kind of trellis-work of conducting material, with the mesh-wires more or less thick or closely spaced, coated or covered with an insulating substance (quartz or the like) which could not absorb or tap off any electro-dynamic current.

What I claim is:-

1. In combination with a mercury vapor or are type rectifier having an anode and a control electrode, an auxiliary vapor rectifier apparatus means for extracting a harmonic voltage from the trcde, an auxiliary vapor rectifier apparatus, means for applying said harmonic voltage to said control electrode in superposition on an alternating voltage of the same frequency as the anode voltage, and means for varying said harmonic voltage in magnitude and in phase while said alternating voltage remains fixed in phase relation to said anode voltage.

2. In combination with a mercury vapor or are type rectifier having an anode and a control electrode, an auxiliary vapor rectifier apparatus, a resistance traversed by the rectified current of said auxiliary apparatus, a source of direct current, a high resistance, said source and said high resistance being connected in series as a shunt across said resistance, means for applying to said control electrode the alternating voltage obtained across said resistance, and means for varying said alternating voltage in magnitude and in phase.

3. In a mercury vapor or are type rectifier having anodes and control electrodes, the regulation of the current supplied by the rectifier by applying to said control electrodes a single alternating voltage having a frequency in harmonic relation to that of the anode voltage, said harmonic- .frequency voltage being variable in phase relation to said anode voltage.

4. In a mercury vapor or are type rectifier having anodes and control electrodes, the regulation of the current supplied by the rectifier by applying to said control electrodes an alternating voltage having a frequency which is an even multiple of, more particularly double, that of the anode voltage and variable in phase relation to said anode voltage.

5. In a mercury vapor or are type rectifier having anodes and control electrodes, the regulation of the current supplied by the rectifier by applying to said control electrodes a voltage composed of an alternating voltage of the same frequency as the anode voltage and in fixed phase relation thereto, a constant direct current voltage, and an even harmonic voltage, in particular a second harmonic, said harmonic voltage being variable in phase relation to said anode voltage.

MARIUS LATOUR. 

